Structural Interrogation of Electrosprayed Peptide Ions by Gas-Phase H/D Exchange and Electron Capture Dissociation Mass Spectrometry
Bibliographic record
Abstract
The structural characterization of gaseous biomolecular ions remains a challenging task. Here, we employ a combination of gas-phase hydrogen-deuterium exchange (HDX) and electron capture dissociation (ECD) mass spectrometry for gaining insights into the properties of two electrosprayed peptides: RA(9)K and RG(9)K. Mass analysis of ECD fragments provides spatially resolved labeling information. ND(3)-mediated HDX at peptide termini and amino acid side chains goes to completion within 1 s. Backbone amide labeling occurs more slowly, and proceeds in a structurally sensitive fashion. HDX is more extensive for RG(9)K than for RA(9)K, suggesting a more "open" conformation for the former. Residues 7-10 in RA(9)K are strongly protected, which indicates the presence of stable backbone hydrogen bonds at these sites. Our findings are consistent with the results of previous ion mobility measurements and computational investigations. Overall, it appears that the combination of gas-phase HDX and ECD represents a viable approach for uncovering structural features of biomolecular ions in the gas phase.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".